Pedigree analysis of Czech Holstein calves with schistosoma reflexum

Pedigree analysis was carried out in 29 cases of SR in Czech Holsteins and Holstein crosses. Genetic relationship was evaluated and inbreeding coefficients calculated. Pedigrees of 15 Czech Holsteins fathering non-SR affected calves were used for comparison.Twenty-one cases occurred in one pedigree founded by three sires while three SR calves occurred in another pedigree with a common grandfather. The sex ratio between affected males and females was 11:6. Affected calves shared common ancestors different from those shared by the unaffected calves. The inbreeding coefficient in the SR affected calves was not increased compared to unaffected calves.The findings are consistent with SR being inherited autosomal recessively. Further studies are however needed to confirm this and therefore a breeding trial is recommended where a suspected heterozygous sire is mated to closely related females.Schistosoma reflexum (SR) is congenital syndrome briefly characterized by severe abdominal fissure with total eventration of viscera, marked dorsoflexion, and ankylosis of the spine and limbs. It occurs in all food animals, but is most common in cattle. SR usually requires assisted delivery, in most cases Caesarean section or foetotomy [1,2]. Although SR is rare, the high risk of dystocia in such cases is a welfare problem and the required veterinary assistance has a negative economic impact on farm economy.Most studies of SR have dealt with the morphology of the syndrome [2-4], although some authors have also proposed a genetic background [5]. However, conclusive evidence has not yet been provided.This study was performed to further evaluate a possible genetic aetiology through pedigree analysis of multiple SR cases in Czech Holstein cattle.Twenty-nine cases of SR diagnosed and reported by veterinary surgeons to the Czech surveillance program for bovine genetic disorders were included. The study was limited to Holstein and Holstein-crossbred calves fathered by sires born between Janu